The present invention relates generally to drug pump testing systems and methods for drug pumps. In particular applications, drug pump testing systems and methods are provided for calibrating the pump mechanism of the pump. Testing systems and methods are also provided for testing one or more sensors on the pump.
In medical applications, fluid must sometimes be conveyed intravenously to a patient undergoing treatment. The fluid is usually contained in a fluid reservoir, typically a bag, conveyed through a tube, and injected into the patient""s vein. Many times, regulating the volume and rate the fluid is conveyed to the patient is advantageous, and in such instances, traditionally, infusion pumps are employed.
One such infusion pump effective for the application described above is disclosed is U.S. Pat. No. 4,559,038 (xe2x80x9cthe ""038 patentxe2x80x9d), the disclosure of which is herein incorporated by reference. The infusion pump disclosed therein regulates the conveyance of fluid from a fluid reservoir to a patient. In accordance with the infusion pump of the ""038 patent, a reservoir containing fluid for treating a patient is held in a cassette having a pressure plate immediately adjacent to a pump control module. A tube for conveying the fluid couples the fluid reservoir and the patient and provides a medium for conveying the fluid. A pump control module regulates the rate fluid is conveyed to the patient by applying physical pressure to the tube, thereby restricting the volume of fluid flow. In the ""038 patent, the pump control module includes a pumping mechanism having tube engaging members which engage and squeeze the tube against the pressure plate of the cassette. The tube engaging members of the ""038 patent include an expulsor and an inlet valve and an outlet valve on opposite sides of the expulsor.
Infusion pump systems and methods, particularly when used in medical applications, must perform with accuracy. Using an infusion pump to deliver medication and/or other fluid to a patient requires an accurate pumping mechanism. To ensure that an infusion pump performs with the requisite accuracy, testing is conducted on infusion pumps used for these applications. Typically, the testing equipment used and methods performed to measure the accuracy of the infusion pump and associated pumping mechanism are expensive and cumbersome. In such typical setups, a calibrated scale, a fluid reservoir, a recipient container, and a timing device are necessary equipment. Further, performing this testing procedure requires a significant amount of time for assembly and disassembly, consumes space, and requires a skilled operator to correctly perform the test. U.S. Pat. No. 5,669,877 (xe2x80x9cthe ""877 patentxe2x80x9d), commonly owned with the ""038 patent, relates to automated testing of drug pumps with a testing device and a computer. The disclosure of the ""877 patent is hereby incorporated by reference.
The pump control module may include various sensors used during pump operation. It is desirable to verify the proper functioning of the sensors. Examples of sensors used with infusion pumps include cassette identification sensors and tube occlusion sensors. U.S. Pat. No. 5,531,697 (the ""697 patent) concerns a pump including a cassette identification system having one or more sensors for sensing indicia on the cassette relating to the type of drug or fluid to be pumped, concentration, volume, the amount of drug pumped per activation of the pump, i.e., tube size. Also, the cassette identification system can be used to prevent operation of the pump if an unauthorized cassette is coupled to the pump control module. U.S. Pat. No. 5,695,473 (the ""473 patent) concerns a pump having an occlusion sensing system with at least one sensor. U.S. Pat. No. 4,650,469 (the ""469 patent) also concerns a pump having an occlusion sensing system. These patents are also commonly owned with the ""038 patent, and the disclosures are hereby incorporated by reference.
There is a continued need for further testing systems and methods, especially for pump mechanism calibration and sensor testing.
In one aspect the present invention comprises a calibration cassette for a drug pump testing system. The calibration cassette comprises a housing supporting a reservoir bag wherein the reservoir bag contains a known test volume. The housing of the calibration cassette has at least one opening for a tube communicating between the reservoir bag and a collection area to pass, and the tube is preferably positioned along a top surface of the calibration cassette. The collection area is housed substantially within the housing of the calibration cassette. A variation of this calibration cassette comprises a reservoir bag having a dual chamber: a fluid chamber and a collection chamber separated by a barrier.
Another aspect of the drug pump testing system of the present invention comprises a pump control module having tube engaging members and coupled to a calibration cassette. The calibration cassette of the drug pump testing system houses a reservoir bag comprising a fluid chamber and a collection area, and the fluid chamber contains a known test volume. The reservoir bag is coupled with a tube communicating between the fluid chamber and the collection area. The tube is positioned along the calibration cassette and positioned for occlusion by the tube engaging members.
In yet another aspect, the present invention comprises a method for calibrating a pump. This method comprises steps including providing a pump control module coupled to a calibration cassette. The calibration cassette supports a fluid chamber which contains a known test volume. A tube communicating between the fluid chamber and a collection area and an occlusion sensor is also provided. The tube is positioned for occlusion by tube engaging members of the pump control module, and the known test volume is pumped from the calibration cassette to the collection area. Each stroke of the tube engaging members is counted to obtain a number of pump strokes. After the known test volume has been completely pumped from the fluid chamber, the pump control module is stopped. A display of the pump control module displays indicia indicative of the accuracy of the pump control module.
Another aspect of the invention concerns a method for testing a drug pump comprising the steps of providing a pump control module, comprising at least one occlusion sensor, coupled to a bottom surface of a calibration cassette having a sensor testing mode cassette identification projection and at least one pressure protrusion delivering a known pressure. The output of the at least one occlusion sensor is compared with the known pressure. Then, the bottom surface of the calibration cassette is uncoupled from the pump control module, and the top surface of the calibration cassette is coupled to the pump control module. A tube is provided so that the tube communicates between a known test volume and a collection area and is positioned for occlusion by tube engaging members of the pump control module. The volume of the known test volume is input into the pump control module, and the known test volume is pumped from the calibration cassette to the collection area. Once the pumping is complete as sensed by the one or more occlusion sensors, the pumping step is stopped. The accuracy of the pump control module is determined by reading the difference between the product of the number of pump strokes and the nominal pump stroke volume and the known test volume as output by the pump.